//
//  intmath.hpp
//  VideoParse
//
//  Created by xiaerfei on 2020/5/1.
//  Copyright © 2020 erfeixia. All rights reserved.
//

#ifndef intmath_hpp
#define intmath_hpp
#include <stdint.h>


namespace intmath {
/* We use the De-Bruijn method outlined in:
 * http://supertech.csail.mit.edu/papers/debruijn.pdf. */
inline int ff_ctzll_c(long long v) {
    static const uint8_t debruijn_ctz64[64] = {
        0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
        62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
        63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
        51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
    };
    return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386DU) >> 58];
}
}

#endif /* intmath_hpp */
